import { BufferLocation, BufferSize, Char, Color } from "./base.ts";
import { Display } from "./display.ts";

/**
 * Base for all web-based terminal displays
 */
class WebDisplay implements Display {
  readonly document = (window as any).document;

  async getSize(): Promise<BufferSize> {
    return { w: 40, h: 20 };
  }

  async setupPalette(colors: readonly Color[]): Promise<readonly Color[]> {
    return [];
  }

  async clear(): Promise<void> {
  }

  async setCursorVisibility(visible: boolean): Promise<void> {
  }

  async setChar(at: BufferLocation, char: Char): Promise<void> {
  }

  async getKeyStrokes(): Promise<string[]> {
    return [];
  }
}

/**
 * Basic terminal display using a single "pre" tag
 */
export class PreTerminalDisplay extends WebDisplay {
  element: any;

  async clear(): Promise<void> {
    if (!this.element) {
      this.element = this.document.createElement("pre");
      this.document.body.appendChild(this.element);
    }

    const { w, h } = await this.getSize();
    const line = Array(w).fill(" ").join("");
    this.element.textContent = Array(h).fill(line).join("\n");
  }

  async setChar(at: BufferLocation, char: Char): Promise<void> {
    const { w, h } = await this.getSize();
    const offset = at.y * (w + 1) + at.x;
    const text = this.element.textContent;
    this.element.textContent = text.slice(0, offset) + char.ch +
      text.slice(offset + 1);
  }
}

/**
 * DOM terminal display, using one div per char
 */
export class DOMTerminalDisplay extends WebDisplay {
}